Illuminated keyboard

ABSTRACT

A light guide is provided for illuminating innumerable constructions, but which is ideally suited for illuminating the keys of a keyboard. The light guide includes a translucent planar plate having a top, a bottom and sides. Further, the light guide includes one or more cavities which project upwardly into the translucent plate from its bottom surface. The cavities are hollow or filled with a translucent material so that the translucent plate and the one or more cavities form translucent interfaces where the cavities interface with the plate. The light guide also includes a reflector which covers the plate bottom and cavity openings.

RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 12/386,075 filed on Apr. 13, 2009, now abandonedwhich in turn is a continuation-in-part of U.S. patent application Ser.No. 11/974,670 filed Oct. 15, 2007, now abandoned which in turn is acontinuation-in-part application of U.S. patent application Ser. No.11/038,308 filed Jan. 18, 2005, now U.S. Pat. No. 7,283,066 issued Oct.16, 2007, which in turn is a continuation-in-part application of U.S.patent application Ser. No. 10/294,396 filed on Nov. 14, 2002, now U.S.Pat. No. 6,918,677 issued Jul. 19, 2005, which in turn is acontinuation-in-part application of U.S. patent application Ser. No.09/899,960 filed on Jul. 6, 2001, now abandoned, which in turn is acontinuation-in-part application of U.S. patent application Ser. No.09/836,628 filed on Apr. 16, 2001, now U.S. Pat. No. 6,467,924 issuedOct. 22, 2002, which in turn is a continuation-in-part application ofU.S. patent application Ser. No. 09/500,735, filed on Feb. 9, 2000, nowU.S. Pat. No. 6,217,183 issued Apr. 17, 2001, which in turn is acontinuation application of U.S. patent application Ser. No. 09/396,141,filed on Sep. 15, 1999, now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates generally to keyboards, includingtypewriter and computer keyboards.

More specifically, the present invention relates to keyboards havingilluminated key members.

Conventional keyboards include a plurality of key members which displaysymbols, such as alphanumeric keys, on their top surfaces. Moreover,typical modern keyboards, such as those found in cellular telephones,Automatic Teller Machines (ATMs), electric typewriters and computersutilize a make-and-break electrical circuit which is activated bydepression of a key member for identifying a particular symbol embeddedon the top of the key member.

A problem with prior art keyboards is that it is often difficult todiscern the symbol appearing on the top of the key member under poorlighting conditions. This causes the keyboard operator to memorize thekey locations or to strain their eyes to operate the keys of thekeyboard under low light conditions. This has become a much greaterproblem in present day society as keyboards have become necessary foreveryday use and as keyboard use is not limited primarily to operationby workers in business offices as in the past. As a result of thisexpansion of keyboard use, more and more operators have less training onkeyboards, and correspondingly many keyboard operators utilize a “huntand peck” style of keyboard operation.

Moreover, the advent of laptop and notebook computers has resulted inthe use of keyboards at places where they were not previously operated.Often these places provide limited light making it difficult forkeyboard operators to quickly and easily operate the keyboard. Forexample, it is a common sight on commercial aircraft to see a passengerslowly hunt and peck at their keyboards continuously looking at the keymembers to verify that they are in fact pressing the correct keys.

Accordingly, it is clear that there is a need for an apparatus thatmakes keyboard key members more discernable in low light conditions.Backlighting is commonly used in rubber keypads, membrane switches,rigid panels and the like to make them more visible and discernable.These keypad panels typically make use of light emitting crystals(LECs), light emitting diodes (LEDs), and/or fiberoptics for thispurpose. Most prior backlit keyboards utilize a light source which istypically transmitted via a fiberoptic cable to the key members of akeypad. For example, U.S. Pat. No. 5,034,602 issued to Garcia, Jr. etal. discloses an optically activated keyboard which uses fiberopticcables to transmit light to translucent key members. The light istransmitted through the translucent key members where it is emitted fromthe top of the key cap. Similarly, U.S. Pat. No. 3,886,544 issued toNarodny and U.S. Pat. No. 5,097,396 issued to Myers disclose keyboardswhich use backlighting. Each key member in connection to a fiberopticcable which transmits light to a respective key member which thereaftertransmits light from the top of the key cap. Additional keyboard andkeypad techniques include the LED and LEC backlighting commonly utilizedfor alarm activator and deactivator keypads wherein each key includes aseparate LED or LEC structure embedded in or behind the key member.Unfortunately, it is extremely difficult to route fiber optics to thekeyboard keys of today's computer systems. For example, it would beparticularly difficult to route fiberoptic cables and provide a lightsource to the key members of today's notebook computers and palm-sizedcomputer systems.

In addition, the light sources for use with prior art backlit keyboardsrequire substantial power and in some cases, a fan for cooling whichdraws additional power. These constructions are prohibitive for portablecomputers such as laptop and notebook computers which draw on the powerof a rechargeable battery and where power is at a premium.

Recently, the present named inventor, Michael Shipman, developednumerous lighted keyboard and light pipe constructions which are thesubject of U.S. Pat. No. 6,217,183 issued on Apr. 17, 2001; U.S. Pat.No. 6,467,924 issued on Oct. 22, 2002; U.S. Pat. No. 6,918,677 issued onJul. 19, 2005; U.S. Pat. No. 7,172,303 issued on Feb. 6, 2007; U.S. Pat.No. 7,193,535 issued on Mar. 20, 2007; U.S. Pat. No. 7,193,536 issued onMar. 20, 2007; and U.S. Pat. No. 7,283,066 and which are incorporated byreference herein. The keyboard constructions utilize a variety ofelectro luminescent, light transmitting panels and light emitting diodes(LED) for illuminating the keys of a keyboard. For the most part, theseconstructions are satisfactory.

It would be highly advantageous to provide a keyboard having illuminatedkey members which provided improvement in weight and simplicity; wasinexpensive to manufacture; and required low power consumption.

SUMMARY OF THE INVENTION

Briefly, in accordance with the invention, I provide several embodimentsof improved keyboard constructions having illuminated indicia andilluminated key members. The improved keyboard includes indicia, aplurality of key members, and in some embodiments, a light channelingmembrane. The term “keyboard” is intended to be interpreted herein in abroad sense, unless specifically stated otherwise, to include any fingeractivated switch construction including computer keyboards, calculatorand cellular telephone keypads, television remote controllers, and otherhandheld switching devices including depressable keys such as videogames, GPS modules, etc.

In a first of many preferred embodiments, the upper clamshell member ofthe keyboard's housing acts as a light channeling membrane. The lightchanneling membrane and plurality of key members are manufactured ofacrylic plastic, polycarbonate or glass for optical clarity, thoughother materials may be used depending on cost, weight and manufacturinglimitations as would be understood by those skilled in the art. For thisembodiment, the light channeling membrane includes a plurality of bores,with each bore being constructed for receipt of the key shaft of acorresponding key member. Meanwhile, each key member also includes a keycap having a symbol displayed thereon. Each key member shaft isconstructed to extend downwardly and telescopically into a correspondingbore of the light channeling membrane to provide what is commonlyreferred to as a “plunger” type keyboard construction. Light ischanneled through the translucent material of the light channelingmembrane until it is emitted from cylindrical sidewalls into themembrane's bores. Light emitted from the bores' interior sidewalls isreceived onto the exterior of the shafts of the key members andchanneled upwardly through the translucent material of the shaft, to thekey caps which are also constructed of a translucent material. The keycap includes an upper surface having an alphanumeric symbol displayedthereon which is illuminated by light passing through the shaft of thekey member to provide the desired illuminated alphanumeric symbol. Thesymbol can be constructed as light emitting or as opaque with theremainder of the top surface being conversely opaque or light emitting,depending on whether the desired symbol is in either a negative or apositive representation thereof.

In another preferred embodiment of the present invention, the keyboardhousing is constructed partially of a substantially translucent materialfor communicating light rays through said keyboard in the form ofindicia, wherein said indicia is discernible when light rays pass therethrough. The indicia may be an indicator or, for example, correspond toa key member or a group of key members.

The light source may take various forms known to those skilled in theart. For example, the light source may be an incandescent lightbulb,light emitting diode (LED), light emitting crystal (LEC), etc. Moreover,the light source may produce light which can be selectively varied incolor so as to enable the keyboard operator to alter the color of theluminescence of the key members. For example, the light source maycomprise a plurality of diodes with each diode producing differentcolored light. Selective activation and deactivation of the diodes aloneor in combination will produce key members illuminated in differentcolors.

In another preferred embodiment of the present invention, the lightsource is connected to a light pipe located within the keyboard housingfor channeling light to a plurality of key members. The light pipe, alsoknown as a light guide, may be constructed in various shapes and ofvarious materials such as of lengths of acrylic plastic, polycarbonate,or glass. Alternatively, the light pipe may be constructed of one ormore fiberoptic fibers or cables. The light pipes may also beconstructed of one or more different translucent and flourescent coloredmaterials for projecting light of one or more colors upon the keymembers, and for producing alphanumeric characters on the key members ofdifferent colors. An acceptable colored material includes “scintillatingplastic” which is typically an acrylic plastic incorporating differentcolored flourescent dyes.

Preferably, the light pipes are constructed to project light laterallyfrom their exteriors. Where the light pipes are comprised of fiberopticcables, the fiberoptic cables are also constructed to project lightlaterally from their cylindrical exterior as opposed to predominantlyfrom their distal extremities. This can be accomplished by notching,knurling, scratching or in other manners creating flaws in the otherwisesmooth exterior cylindrical surface of the fiberoptic cable. These flawshave been found to interrupt the transmission of light along the lengthof the fiberoptic cable and to transmit light laterally from theexterior surface of the fiberoptic cable, typically opposite the sidewhich has been flawed. For application with the present invention, alight pipe is routed alongside indicia or a plurality of key members.Light transmitted through the light pipe may be transmitted laterallyupon the keyshafts of the key members. The light is then channeledthrough the key members so as to be emitted from the upper surface ofthe key members to illuminate a symbol or character.

In an additional preferred embodiment of the present invention, thelight source is constructed of a substantially planar plate underlyingthe light channeling membrane of the keyboard. An alternativeconstruction for the illuminating sheet of the light source is describedin U.S. Pat. No. 5,045,755 issued to Appelberg and assigned to E-LiteTechnologies, Inc. which is incorporated herein by reference. Theilluminating sheet is a split electrode or parallel plate lampconsisting of a main body sandwiched between first and second conductivelayers. Application of an alternating current to the planar sheetprovides a luminescent sheet which can be adhesively attached to thebottom of the keyboard light channeling membrane. Moreover, theilluminating sheet is sufficiently thin as to not require significantmodification to existing computer keyboard designs.

An additional construction of the luminescent sheet can be obtained fromMKS, Inc. located in Bridgeton, N.J., USA under the trademarkdesignation Quantaflex™. The Quantaflex™ material is anelectroluminescent lamp including luminescent phosphors embedded in thedielectric medium of a capacitor constructed in the form of a sheet.Electrodes, including at least one translucent electrode, form the topand bottom layers of the Quantaflex™ material. Upon application of analternating current to the electrodes, the phosphors give off photonsproducing light in the visible spectrum. An advantage of the Quantaflex™material is that the phosphors can be selectively encapsulated betweenthe electrode layers of the luminescent sheet so as to selectivelyproduce patterns of light emitted from the luminescent sheet. Forexample, for application with the present invention, it is preferredthat the Quantaflex™ material be constructed to produce light only belowand/or immediately adjacent to the key members so as to reduce powerconsumption.

In still additional embodiments, the luminescent sheet is constructed ofone of the rapidly developing technologies directed to Organic LightEmitting Devices (OLED), Transparent Organic Light Emitting Devices(TOLED), or Flexible Organic Light Emitting Devices (FOLED).Descriptions of these technologies are available to those skilled in theart and will not be described in further detail herein.

In an additional preferred embodiment, the luminescent sheet isconstructed as a light guide connected to a light source. The lightguide is made of a substantially translucent material, such as anacrylic plastic, polycarbonate, epoxies and glass, connected to anindependent light source, such as light emitting diodes, light emittingcrystals, etc. For this embodiment, the light channeling luminescentsheet operates as a planar light pipe for channeling light from thelight source to the key members.

In one embodiment, a light guide of the present invention includes asubstantially planar translucent plate having a top, a bottom and one ormore sides. For example, a circular light guide will have one side, atriangular light guide will have two sides, while a light guide forilluminating a keyboard would typically be rectangular and have foursides. Preferably, but not necessarily, the plate is continuous and hasno holes, or very few holes, which can significantly deteriorate theplate's light carrying properties. Moreover, the translucent plate ispreferably flat and of uniform thickness. However, as understood bythose skilled in the art, the plate may be curved and vary in thicknessdepending on design requirements. The planar plate may be made from anynumber of materials such as glass or clear plastics including ABS,acrylics, polycarbonate, etc. In preferred embodiments, the planar plateincludes sides which are curved or rounded so as to avoid any sharpedges at the transition of the top or bottom with the sides which canalso deteriorate the plate's light carrying properties. Alternatively,the edge can include a recessed to form an external concavity which ispreferably sized to receive any wiring, such as wiring for any lightsources.

The light guide further includes one or more cavities formed into thebottom of the planar plate. The cavities may be formed by preforming thecavities into the planar plate in an injection molding process.Alternatively, the cavities can be machined into the planar plate usingdrilling or lathe equipment. In addition, the cavities may be any numberof shapes including, but not limited to, pyramid, ellipsoid, parabolic,cone, hemispheric or cubic. Moreover, where the light guide includes aplurality of cavities, the cavities may be of different sizes anddifferent shapes.

The light guide of the present invention also includes a reflector whichunderlies the translucent plate's bottom side and which covers theplurality of cavities. Preferably, the reflector also covers thetranslucent plate's sides and upper surface, except for where light isintended to be emitted, such as under the keys of a keyboard. Thereflector may be made out of various materials such as Mylar, paper orother metals. However, it is important that the reflector include ahighly reflective surface, and thus it is preferably mirrored, white,light grey, silver, metallic silver or metallic gold so that lightstriking the reflector will reflect off the reflector as opposed to bebeing absorbed or refracted. In addition, the reflector may incorporateglowing or phosphoric elements which will emit light upon experiencinglight from another light source.

The reflector may be affixed adjacent to the translucent plate usingvarious constructions known to those skilled in the art. However, in apreferred embodiment the reflector is attached to the translucentplate's underside using an adhesive which is either highly reflective ortranslucent. Alternatively, the reflector can be positioned andmaintained in place using the overall construction of the keyboardhousing which will maintain various components in place. Screws may beused to affix the reflector and translucent plate within a desiredconstruction. However, it is preferred that the screws be reflective andof minimal size if inserted into holes formed through the reflector andtranslucent plate.

As a result of the reflector covering the cavities opening, the cavitiesare substantially sealed chambers within the planar's sheet. Formanufacturing purposes, these chambers will typically be filled withair. However, various other translucent materials may be placed withinthe cavities, such as clear or colored plastics. Alternatively, thecavities can be filled with translucent phosphoric materials which willproduce a glowing material or produce an alternative color upon lightstriking the material. Translucent plastics which produce a glowing orphosphoric appearance are sold under the generic name of “scintillatingplastics”. Where the translucent plate includes a plurality of cavities,the cavities may be filled or not filled, with a variety of materialssuch as plastics of different colors or phosphoric materials ofdifferent colors to produce light guide having points of illumination ofdifferent colors and luminosity.

The light guide of the present invention further includes a light sourcefor emitting light which is received by the translucent plate. The lightsource may be any of numerous light sources known to those skilled inthe art including electro-luminescent panels, incandescent light bulbs,light emitting diodes (LEDs) and light emitting crystals (LECs).However, for cost and efficiency, it is preferred that the light sourceof the present invention be one or more LEDs. The light sources may bepositioned in any way so as to shine light onto or into the translucentplate. For example, the light source may be positioned immediatelyadjacent to the translucent plate's edges. Alternatively, the lightsources may be positioned to project into a recess formed into thetranslucent plate's upper or lower surfaces or into the translucentplate's sides.

In operation, light is transmitted into the translucent plate. The lightis then reflected off the reflector throughout the translucent plate'sinterior until striking the interface of the translucent plate with acavity. Because of the translucent properties of both the cavity and thetranslucent plate, significant amounts of light will be transmitted fromthe translucent plate into the cavity by direct transmission or byrefraction depending upon the light's angle to the cavity's interfaceand depending on material properties. Preferably the cavity has a cone,parabolic or ellipsoid shape causing light to project downwardly tostrike the reflector. Upon striking the reflector, light is reflectedupwardly through the cavity to translucent plate's interface where lightpasses again into the translucent plate until being transmitted from thetranslucent plate's upper surface.

As would be appreciated by those skilled in the art, various factorsincluding the translucent plate's material and angle of light strikingthe sheet cavity interface will cause some light to reflect, as opposedto refract into the cavity. As a result of the cavities dome-lightshape, much of the light will be caused to reflect upwardly through theplate to be transmitted from the translucent plate's upper side. As aresult of the light reflected and refracted from the plate and cavityinterfaces, the light guide will produce one or more illuminated shapesformed on the translucent plate's upper side which correspond in sizeand placement to the underlying cavities.

Typically, the light producing cavities will be centered directly underthe keys of a keyboard. However, in an alternative preferred embodiment,the cavities are displace off-center from directly below a key member.In particular, it has been found that backwardly displacing the lightproduced under a key approximately 1-5 mm. can make the characters, alsoreferred to herein as indicia, formed on a key to appear more luminous.The amount of offset can be determined by one skilled in the art due tothe viewing angle of a person operating the keyboard and due to theplacement of characters on the key members.

In still an additional embodiment of the luminescent planar sheet whichis ideal where the luminescent sheet needs to be particularly thin suchas is required for laptop keyboards, the light guide does not include ancavities. Instead, the light guide has a flat underside surface butincludes reflective members positioned underneath each of the keys. Eachreflective member is reflective causing light, such as provided by LEDspositioned along the sides of the light guide, to reflect upward towardeach overlying key.

In preferred embodiments, the reflective members are comprised ofreflective paint painted onto the bottom of the light guide, or arecomprised of thin reflective paper or plastic or the like, affixed underthe keys. Preferably, an additional reflective sheet covers theunderside of the light guide as well as the reflective members. Alsopreferably, the reflective members provide greater light diffusion thanthe reflector. For example, it has been has discovered that “flat” whitereflector members provide better illumination to the keys than glossywhite reflector members having lesser light diffusion.

Thus, a preferred light pipe includes a plainer sheet of plasticmaterial without any underlying deformities forming the light guide.Instead of cavities, the underside is covered by a first layer ofreflective members positioned under each key such as in the form ofreflective white circles or squares ¼-¾ inch across, with a preferredwidth of approximately ½ inch. The white reflective members arepreferably “flat white” in appearance to provide light diffusion. Thereflective members are then covered by a sheet of glossy paper or thelike which is mirrored, white, light grey, silver, metallic silver ormetallic gold in appearance have lesser diffusion than the overlyingreflective members.

The light guides of the present invention may be incorporated into thevarious keyboard constructions having illuminated indicia andilluminated key members. A few such keyboards are described as follows.A preferred keyboard includes a plurality of key members, and a lightchanneling membrane. The key members and light channeling membrane areconstructed of a substantially translucent material capable ofchanneling light rays. In addition, the keyboard of the presentinvention includes a light source optically connected to the lightchanneling membrane. In operation, the light source produces light rayswhich are received by the light channeling membrane within the keyboardhousing, or is positioned adjacent the indicia or plurality of keymembers. The light rays are channeled through the light channelingmembrane to the indicia or key members which receive the light rays attheir lower extremities and which channel the light rays upwardly totheir top surface. Light is then emitted from the top of the key memberto either provide illumination around an opaque construction of a symboldisplayed on the top surface of the key member, or in the alternative,to emit light rays in the shape of the symbol itself, as in the case ofkeyboard indicia.

In still an additional preferred embodiment, the luminescent sheet isconstructed of a plurality of fiberoptic cables laid side by side toform a planar sheet. The ends of the cables are positioned adjacent toone or more LEDs or LECs so that emitted light is channeled through thefiberoptic cables. Again, the fiberoptic cables are notched, knurled,scratched or the smooth exterior is otherwise flawed to interrupt thetransmission of light along the length of the fiberoptic cables and totransmit light laterally from the exterior surface of the fiberoptic.

Where the keyboard of the present invention utilizes an illuminatingsheet for providing light to the key members, the illuminating sheet maybe formed with a plurality of holes. The luminescent sheet is thenaffixed below the light channeling membrane with the holes of theluminescent sheet underlining the bores projecting through the upperclamshell member of the keyboard, which may also function as a lightchanneling membrane. This construction permits the shafts of the keymembers to project through the clamshell bores and through the holes ofthe illuminating sheet. Where the keyboard is constructed for use with acomputer, disposed below the illuminating sheet is an elastomericdiaphragm, for biasing the key members upwardly, and a keyboard circuitboard. The circuit board includes a plurality of switches which arecloseable upon pressure application such that depression of the keymembers causes the respective key shafts to project downwardly throughthe membrane bores and illuminating sheet holes to depress theelastomeric diaphragm to, in turn, activate the circuit board switches.The closure of a particular circuit board switch results in acorresponding signal being sent to the computer indicating that aparticular key member has been depressed.

In an additional embodiment of the present invention, the planarluminescent sheet is disposed between the elastomeric diaphragm andcircuit board. The elastomeric diaphragm is manufactured of atranslucent material so that light emitted upwardly from the luminescentsheet shines upon the bottoms of the key member shafts, and preferablyupon the bottom of the upper clamshell member of the keyboard which isalso preferably manufactured of a translucent material. For thisembodiment, the elastomeric diaphragm and upper clamshell membercooperate to function as a light channeling membrane to transmit lightfrom the light source to the key members. The light is then channeledthrough the key members to be transmitted from the tops of their keycaps.

In still an additional embodiment of the present invention, the keyboardis constructed with the planar luminescent sheet positioned to underliethe elastomeric diaphragm and circuit board of the keyboard. Theelastomeric diaphragm and circuit board are manufactured ofsubstantially translucent materials for permitting light emitted fromthe luminescent sheet to project upwardly through the circuit board andelastic diaphragm to strike the bottom extremities of the key members.It is preferred that the upper clamshell member of the keyboard also betranslucent for channeling light rays to the sidewalls of the key membershafts. However, for this embodiment, the elastic diaphragm and circuitboard of the keyboard also function as the light channeling membrane.Light emitted from the planar sheet is channeled through the translucentmaterial of the elastomeric diaphragm and circuit board to the keymembers. The light is then transmitted through the key members to thekey member's upper surface where it is emitted from the top of the keycap in the shape of a character displayed on the key cap.

In a preferred embodiment of the keyboard wherein the planar luminescentsheet is positioned to underlie the elastic diaphragm and circuit boardof the keyboard, the keyboard is ideally constructed for use as a laptopkeyboard or keyboard desiring short key stroke travel. For thisembodiment, the keyboard includes scissor actuators for stabilizing eachkey to provide upward and downward movement and which are of the typecommonly found within laptop computers and which are well understood bythose skilled in the art. Each scissor actuator includes a pair ofscissor arms which are rotationally connected at or near their midpointsto permit the arms to rotate in a scissor-like manner. Like otherconstructions described herein, a substantially translucent elastomericdiaphragm including elastomeric domes underlies the key members forbiasing the keys upwardly. A seat underlies the elastomeric domes forsupporting and engaging the bottom extremities of the scissor actuators.To this end, the seat includes clips which project through holes formedin the elastomeric diaphragm to engage and connect to the bottomextremities of the scissor actuators. As would be understood by thoseskilled in the art, the seat clips will project above the top of theelastomeric diaphragm and the elastomeric domes may project down belowthe bottom of the seat when a key is depressed. However, the elastomericdiaphragm and accompanying domes are predominantly above the seat, andare described accordingly herein. The seat may be made of translucentplastic, which functions as a translucent upper clamshell member, or theseat may be made of non-translucent metal having sufficiently largeholes for the passage of light.

A substantially translucent circuit board is positioned under the seatfor the creation and transmission of signals upon depression of keymembers. The seat includes holes below each key allowing for thedepression of keys to force the elastomeric domes through the seat toengage the circuit board to create electronic signals.

A planar luminescent light source is positioned under the circuit boardfor transmitting light upwardly through the circuit board, seat, andelastomeric domes into the key members. The planar light source mayinclude LED or LEC systems in adjoining relationship to the lightchanneling membrane or light pipe. In a preferred embodiment, theluminescent planar luminescent sheet underlies the keys, elastomericdiaphragm, seat and circuit board.

In a preferred embodiment, where the upper clamshell member istranslucent, it is preferred that the keyboard be constructed or coatedwith an opaque material in the interstitial regions between the keymembers so that light does not project upwardly between the key memberswhich would cause visual glare to the keyboard operator or which wouldotherwise detract from the relative luminescence of the symbolsdisplayed on each of the key members.

Preferably, substantial portions of the keyboard and key members arecoated on their exterior surfaces with a reflective opaque coating suchas paint or the like where light is not intended to be emitted fromtheir exteriors. More particularly, it is preferred that the key membersand upper clamshell member are coated with a reflective paint forreflecting visible light, which would ordinarily be emitted from the keymembers and upper clamshell member or substantially absorbed by asubstantially non-reflective material. Thus, traditional non-reflectivepaints and coatings such as dark grey, black or blue are preferablyavoided. Meanwhile, diffuse reflective coatings such as light grey,white, and silver are preferred, as are coherent reflective coatingssuch as metallic silver, metallic gold and other shiny metallic colors.Alternative substantially reflective coatings can be selected by thoseskilled in the art without undue experimentation. In practice, much ofthe visible light, which would ordinarily be lost, is reflected ineither a diffuse or coherent manner back into the upper clamshell memberor key members until projected from the tops of the key caps to provideenhanced luminosity of the characters formed on the key caps.

In still an additional preferred embodiment, the key caps and clamshellmember include two coatings of paint or the like. The initial firstcoating utilizes a highly reflective coating, such as appearing lightgrey, white, silver, and metallic coatings such as silver, gold andother shiny metallic colors, to reduce light absorption and reflect thevisible light back into the translucent material until transmitted fromthe key caps. Meanwhile, a second coating of an alternative paint orother material is applied over the first coating. The second coating mayalso be reflective. However, it is preferred that the second coating isless reflective of visible light than the first coating, and preferablyis a substantially non-reflective dark dull color such as dark grey,black or blue.

Accordingly, it is an object of the present invention to provide animproved light distribution construction, such as a light guide, whichis less expensive than previous designs.

It is an object of the present invention to provide a light guide thatcan be incorporated into a wide variety of products including, but notlimited to, dashboards, automatic teller machines (ATMs), airplane andspacecraft cockpit, calculator and cellular telephone keypads,television remote controllers, video games and GPS modules, etc.

It is also an object of the invention to provide a light guide for akeyboards having illuminated key members suitable for use with today'scomputer systems including portable computers.

It is thus an object of the present invention to provide an inexpensiveand simple way to construct a keyboard having illuminating indicia orkeys.

It is also an object of the present invention to provide a keyboardhaving illuminated indicia or key members suitable for use with today'scomputer systems including portable computers.

Moreover, it is an object of the present invention to provide a keyboardhaving illuminated indicia or key members which does not require routingof fiberoptic cables to each key member.

These and other and more specific objects and advantages of theinvention will be apparent to those skilled in the art from thefollowing detailed description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a computer including the keyboard of theprior art;

FIG. 2 is a cutaway view of the keyboard shown in FIG. 1;

FIG. 3 is a perspective view of a preferred embodiment of a key memberfor use with the keyboard having illuminated keys of the presentinvention;

FIG. 4 is a perspective cutaway view of the translucent light channelingmembrane for use with the keyboard having illuminated keys of thepresent invention illustrating a light source as an LED or LECcomponent;

FIG. 5 is a perspective cutaway view of the translucent light channelingmembrane for use with the keyboard having illuminated keys of thepresent invention illustrating a light source as one or more fiberopticcables embedded in the translucent light channeling membrane;

FIG. 6 is a cutaway view of a preferred keyboard having illuminated keysof the present invention wherein the light source is a planarilluminating sheet underlying the light channeling membrane of thekeyboard;

FIG. 7 is an exploded view of the keyboard having illuminated keys ofthe present invention in which the light source is a planar illuminatingsheet underlying the light channeling membrane of the keyboard;

FIG. 8 is a cutaway view of a preferred keyboard having illuminated keysof the present invention wherein the light source is a planarilluminating sheet underlying the diaphragm and circuit board of thekeyboard;

FIG. 9 is an exploded view of the keyboard having illuminated keys ofthe present invention in which the light source is a planar illuminatingsheet underlying the diaphragm and the circuit board of the keyboard;

FIG. 10 is an exploded view of the keyboard having illuminated keys ofthe present invention in which the light source is a planar illuminatingsheet positioned between the elastomeric diaphragm and circuit board ofthe keyboard;

FIG. 11 is a perspective exploded view of a preferred keyboard in whicha cylindrical light pipe is positioned adjacent to the clamshellsidewall for transmitting light upon the side of the key shaft of a keymember;

FIG. 12 is a side cut-away exploded view of the keyboard shown in FIG.11 in which light pipes are positioned adjacent to two rows ofdownwardly projecting clamshell sidewalls for transmitting light uponthe sides of a plurality of key shafts for illuminating a plurality ofkey members;

FIG. 13 is a top perspective view of a top clamshell member in which alight pipe is embedded therein for transmitting light adjacently uponthe sides of a plurality of keys for illuminating a plurality of keymembers;

FIG. 14 is an exploded view of a keyboard having illuminated indicia inwhich the light source is a planar illuminating sheet positioned belowthe elastic diaphragm and circuit board of the keyboard;

FIG. 15 is a cross-sectional view of a keyboard having illuminatedindicia and illuminated key members whereby a light source is a lightpipe positioned lateral to the key member and below the keyboard's upperclamshell member;

FIG. 16 is a to view of a keyboard having illuminated indicia whereinthe space bar includes a luminescent line extending laterally across thekey member;

FIG. 17 is a to view of a keyboard having illuminated indicia whereinthe space bar includes a luminescent decorative design in the form of acompany trademark extending laterally across the key member.

FIG. 18 is a bottom perspective view of a light guide of the presentinvention which can be incorporated into a wide variety of illuminatedstructures;

FIG. 19 is a top perspective view of a light guide of the presentinvention which can be incorporated into a wide variety of illuminatedstructures;

FIG. 20 is a top plan view of a light guide of the present inventionwhich includes various modifications for increasing light transmissionthrough the translucent sheet;

FIG. 21 is a side exploded cut-away view illustrating a light guide ofthe present invention;

FIG. 22 is a side cut-away view illustrating a light guide of thepresent invention of FIG. 21;

FIG. 23 is a side cut-away view illustrating a keyboard and light guideof the present invention including a reflector which covers the top,bottom and sides of the translucent plate;

FIG. 24 is a side cut-away view illustrating a membrane switch keyboardand light guide of the present invention including a reflector whichcovers the bottom and sides of the translucent plate;

FIG. 25 is an exploded bottom perspective view of a preferred planluminescent sheet incorporating diffusive dots;

FIG. 26 is an exploded top perspective view of a preferred planluminescent sheet incorporating diffusive dots illustrated in FIG. 25;

FIG. 27 is a top plan view of a preferred light pipe for use with anplanar luminescent sheet;

FIG. 28 is an exploded side view of a preferred luminescent sheetincorporating diffusive dots illustrated in FIG. 25;

FIG. 29 is a side view of a preferred luminescent sheet incorporatingdiffusive dots illustrated in FIG. 25;

FIG. 30 is a top exploded perspective view of a preferred keyboard ofthe present invention incorporating scissor actuators; and

FIG. 31 is a side view of a preferred keyboard of the present inventionincorporating scissor actuators.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

While the present invention is susceptible of embodiment in variousforms, as shown in the drawings, hereinafter will be described thepresently preferred embodiments of the invention with the understandingthat the present disclosure is to be considered as an exemplification ofthe invention, and is not intended to limit the invention to specificembodiments illustrated.

Referring to FIGS. 1-3, keyboards are required to operate numerousapparatus including computers, typewriters and personal organizers, aswell as aircraft and vehicular instrument panels. A typical prior artkeyboard 7 is shown in FIG. 1 for use with a computer 3. The computer 3also includes a central processing unit 9 and monitor 5. By pressing keymembers 11 on the keyboard 7, one sends signals to the centralprocessing unit 9 instructing the computer 3 to perform variousfunctions.

As shown in FIG. 2, a typical keyboard 7 includes a housing 13comprising an upper clamshell member 15 and lower clamshell member 17.The keyboard 7 further includes a plurality of key members 11 and adiaphragm 19 having elastomeric diaphragm projections 20 for biasing thekey members 11 to a normally upward position. A typical computerkeyboard 7 further includes a circuit board 21 which is disposed belowthe key members 11 and diaphragm 19. The circuit board 21 includes firstand second printed wiring layers 23 and 27 which include engraved orembedded electrical circuits. The printed wiring layers 23 and 27 areseparated by an insulator or dielectric layer 25. The insulator layer 25includes a plurality of holes so that depression downwardly of the keymembers 11 causes the diaphragm projection 20 to be forced downwardlyupon the upper printed wiring layer 23 so that the printed wiring layers23 and 27 can come in contact to open and close distinctive electricalswitches through the holes of the insulator layer 25. Each of theseelectrical switches correspond to different key members 11 so that thekeyboard operator can depress the key members either individually or incombination to send various signals to the computer's central processingunit 9.

With reference to FIGS. 3-7, a keyboard 1 is provided having illuminatedkey members 11. Each key member 11 includes a key shaft 29 and a key cap31. Displayed on the top surface 33 of the key cap 31 is a symbol 35such as an alphanumeric character. For application of the keyboard 1 ofthe present invention, the key member 11 is constructed at leastpartially of a substantially translucent light channeling material sothat light can be received by the outer surfaces of the key shaft 29 andchanneled upwardly to be emitted from the key cap's upper surface 33. Ina first embodiment, light rays are emitted from the symbol 35 itself inwhich the translucent material portion of the key cap 31 extends throughthe key shaft 29 and key cap 31 to the key symbol 35. The remainingportion of the key cap's upper surface 33 is constructed of a non-lightemitting material or covered by an opaque coating 51 (FIG. 3). In thealternative, the entire key cap 31 including upper surface 33 isconstructed of a translucent light emitting material while the symbol 35is formed of a non-light emitting material, depending whether the symbol35 is intended to be displayed as a negative or positive representation.

With reference to FIGS. 4-7, preferably though not necessarily, thekeyboard 1 of the present invention includes a light channeling membrane37. The light channeling membrane 37 underlies the key members 11 and isconstructed to channel light rays 53 from a light source to the keyshafts 29 of the key members 11, which in turn channel the light rays 53along the length of the key shafts 29 to the key cap's upper surfaces33. As shown in FIGS. 6 and 7, the light channeling membrane 37 isincorporated into the upper clamshell portion 15 of the keyboard'shousing 13. This is accomplished by constructing the upper clamshellmember 15 at least partially of a translucent light channeling material.Light rays 53 received upon the light channeling membrane's 37 outersurface are channeled throughout the translucent material to the keymembers 11. Preferably, the upper surface of the light channelingmembrane 37 is coated or otherwise constructed with an opaque coating 51so that only the upper surfaces 33 of the key members 11 are seen toilluminate by the keyboard operator. As shown in FIGS. 6 and 7, in apreferred embodiment, the light channeling membrane 37 includes aplurality of hollow projections 39 having central longitudinal bores 41configured for receipt of the key shafts 29 of the key members 11. Thehollow projections 39 may project upwardly as shown in FIGS. 4-10, ormay project downwardly as shown in FIGS. 11-13, and 15. Preferably, thekeyboard 1 also includes a diaphragm 19 having a plurality ofelastomeric projections 20 for biasing the key members 11 upwardly.

In addition to the specially constructed key members 11 and lightchanneling membrane 37, the keyboard 1 of the present invention includesa light source. For this embodiment, the light source may be embeddedin, positioned alongside, or positioned underneath the light channelingmembrane to communicate light to the light channeling membrane 37. Asshown in FIG. 4, in a first embodiment, the light source is comprised ofone or more light strips 45 which can be either light emitting diodes(LED) or light emitting crystals (LEC) systems or other constructionsknown to those skilled in the art which emit light into (as shown inFIG. 5), or upon the exterior side or bottom surfaces of the lightchanneling membrane 37. With reference to FIGS. 5 and 11-13, in a secondembodiment, the light source is connected to one or more light pipes 47,such as fiberoptic cables, which are constructed to project lightlaterally along their length. In particular, it has been found thatfiberoptic cables 47 provide a highly luminescent surface where thecurved cylindrical surface has been notched, knurled, scratched orotherwise flawed so that the flaws receive light rays from the interiorof the fiberoptic cables 47 and emit those light rays laterally from thefiberoptic cable's exterior surface. For application with the presentinvention, the light pipes 47 are routed alongside, below or embedded inthe upper clamshell member 15, which is preferably at least partiallytranslucent so that light rays 53 channeled from the outer surface ofthe light pipe 47 is received by the translucent material and channeledwithin the translucent region 43 to the key members 11.

For example, as shown in FIGS. 11-13, a light pipe 47 is positionedadjacent to a plurality of key members 11, so that a single light pipecan be used to illuminate a plurality of key members. Again, the lightpipe 47 may be constructed of various materials in various shapes as canbe determined by those skilled in the art. As shown in the figures, thelight pipe 47 is attached to, or formed integral with, the upperclamshell member 15, adjacent the hollow projections 39. Preferably, thehollow projections 39 are constructed to include a portion that is atleast partially translucent to allow light channeled by the light pipe47 to channel into the bores 41 formed by the hollow projections 39 andonto the key shafts 29 of the key members 11. Alternatively, the hollowprojections 39 have openings (not shown) in their sidewalls to allowlight to project laterally from the light pipe 47 through the openingsand onto the exterior of the key shafts 29 of the key members 11. Thelight channeled by the light pipe 47 strikes the sides of the key shafts29 and is transmitted through the translucent material of the key member11 to be projected from the top of the key cap 31 in the form of analphanumeric character 35. Where the keyboard is constructed with anelastic diaphragm 19 having elastic projections 20 which project intothe bores 41 formed by the hollow projections, preferably, theelastomeric projections 20 are also constructed of a translucentmaterial so that the elastomeric projections do not impede thetransmission of light from the light pipe 47 to the key members 11 priorto depression of the key members.

In another preferred embodiment of the invention, the light source isconstructed as a substantially planar sheet 49 affixed below the bottomsurface of the light channeling membrane 37. As shown in FIGS. 6 and 7,in one of the preferred embodiments, the planar sheet 49 is constructedwith a plurality of holes 50 which underlie the conical projections 39and longitudinally extending bores 41 of the light channeling membrane37. A shown in FIG. 7, this construction permits the key shafts 29 ofthe key members 11 to telescope downwardly into the bores 41 and throughthe holes 50 of the luminescent sheet 49. Though the key members 11 arenormally biased upwardly by the elastomeric projections 20 of thediaphragm 19, downward depression of the key members 11 by fingertippressure on the key member's upper surfaces 33 causes the key shafts 29to project downwardly through bores 41 and holes 50 until the bottomextremity of the key member 11 forces the diaphragm projections 20 toforcibly close electrical switches 55 in the circuit board 21.

With reference to FIGS. 8 and 9, in an additional preferred embodiment,the planar luminescent sheet 49 underlies both the diaphragm 19 and thecircuit board 21. The diaphragm and circuit board are constructed to besubstantially translucent, and light emitted upwardly by the luminescentplanar sheet 49 is transmitted through the translucent diaphragm andcircuit board to the bottom of the key members 11. Because the keymembers are also manufactured of a translucent material, the light isthen channeled through the key members' shafts 29 to be emitted from thekey's upper surface 33 in the form of a symbol 35.

With reference also to FIGS. 6 and 7, this embodiment has the benefit ofnot requiring that the upper clamshell member 15 of the keyboard bemanufactured of a translucent material so as to function as a lightchanneling membrane 37. Instead, the translucent circuit board 21 anddiaphragm 19 operate as a light channeling membrane by communicatinglight emitted by the planar sheet 49 to the bottom extremities of thekey members 11. Light is then emitted from the upper surfaces 33 of thekey members. Also with reference to FIGS. 6 and 7, this embodiment alsohas the benefit of not requiring that the luminescent planar sheet 49 beformed with holes 50 underlying each of the key members for permittingthe shafts 29 of the key members to project downwardly through the holesso as to engage the diaphragm 19 and circuit board 21. Instead, thekeyboard is constructed with the luminescent planar sheet positioned soas to avoid contact with the moving members of the keyboard, the keymembers and diaphragm. For this embodiment of the present invention, itis preferred that the luminescent planar sheet not include any holes sothat the luminescent planar sheet can provide a maximum of luminosity tothe key members.

With reference to FIGS. 30 and 31, in still another preferred embodimentof the keyboard wherein the planar luminescent sheet is positioned tounderlie the elastomeric diaphragm and circuit board of the keyboard,the keyboard includes scissor actuators 101 for stabilizing each keys 11upward and downward movement. Scissor actuator constructions are wellunderstood by those skilled in the art and only a simplifiedconstruction is illustrated within FIGS. 30 and 31. Alternativeconstructions can be devised by those skilled in the art without undueexperimentation.

As illustrated in FIGS. 30 and 31, each scissor actuator 101 includes apair of scissor arms 103 which are rotationally connected at or neartheir midpoints to permit the arms 103 to rotate in a scissor-likemanner to allow a key to move upward or downward. Like other keyboardconstructions described above, the keyboard includes a substantiallytranslucent elastomeric diaphragm 19 including elastomeric domes 20underling each of the key members for biasing the keys 11 upwardly. Aseat 111 underlies the elastomeric domes 20 for supporting and engagingthe bottom extremities 107 of the scissor actuators. The seat 111engages and connects to the scissor actuators 101 with integrally formedclips 115 which project through holes 109 formed in the elastomericdiaphragm to connect to the scissor arms lower extremities 107. Asunderstood by those skilled in the art, the clips 115 allow the scissorarms to rotate and slide (not shown) so as to permit scissor action ofthe scissor actuator arms 103 and the upward and downward movement ofthe keys 11. The seat 111 may be made of translucent plastic, whichfunctions as a translucent upper clamshell member, or the seat may bemade of non-translucent metal having sufficiently large holes for thepassage of light. Preferably, the seat, including clips, is made of onepiece of stamped metal, or one piece of molded translucent plastic suchas acrylic, polycarbonate, or the like.

As best illustrated in FIG. 31, and as would be understood by thoseskilled in the art, the seat clips 115 project above the top of theelastomeric diaphragm 19 and the elastomeric domes 20 may project downbelow the bottom of the seat when a key is depressed. However, theelastomeric diaphragm 19 and accompanying domes 29 are predominantlyabove the seat 111, and accordingly, the elastomeric diaphragm 19 anddomes 20 are described herein as above the seat 111.

This embodiment of an illuminated keyboard illustrated in FIGS. 30 and31 includes a substantially translucent circuit board 21 positionedunder the seat for the creation and transmission of signals indicatingdepression of keys 11. To this end, the seat 111 includes holes 113below each key 11 allowing for the depression of keys to force theelastomeric domes 20 to engage the circuit board 21 to create electronicsignals.

A planar luminescent sheet 49 is positioned under the circuit board fortransmitting light upwardly through the circuit board 21, seat 111, andelastomeric domes 20 into the keys 11. The planar luminescent lightsource 49 may take any of numerous forms including, but not limited, tothe constructions described herein. However, a preferred luminescentplanar sheet 49 includes a light pipe connected to an independent lightsource such as LEDs 85. In operation, the luminescent planar luminescentsheet 49 transmits light upwardly, in order from bottom to top, throughthe circuit board 21, seat 111, and elastomeric domes 20 to the keys 11.

With reference also to FIG. 10, in an additional embodiment of thepresent invention, the light source 47 is positioned between thediaphragm 19 and circuit board 21. The light source is again constructedin planar form having at least its top side providing luminescence. Theelastic diaphragm 19 is manufactured of a translucent elastomericmaterial so that light emitted upwardly from the light source, in theform of a luminescent sheet 49, shines through the diaphragm projections20 and upon the bottoms of the key member shafts 11. Preferably, forthis embodiment, the upper clamshell member 15 of the keyboard is alsopreferably manufactured of a translucent material so that light emittedfrom the luminescent sheet strikes the underside of the upper clamshellmember 15 and is channeled to the sidewalls of the key members. For thisembodiment, the elastomeric diaphragm and upper clamshell membercooperate to function as a light channeling membrane, transmitting lightfrom the light source to the key members 11.

The light is then channeled through the key members to be transmittedfrom the tops 33 of the key caps 31.

This embodiment has the advantage over the previous embodiment in thatlight emitted from the light source is not transmitted through thecircuit board 21 prior to striking the outer surfaces of the key members11 which could cause diminished luminescence from the key members due tolight reflection, refraction or absorption caused by the opticalproperties of the circuit board. However, this embodiment has thedisadvantage over the prior described embodiment in that the lightsource is positioned between the key members and the circuit board. Thisconstruction requires that the light source be compressed with eachactuation of the keyboard key members unless the light source isconstructed with holes to permit the key members to engage the circuitboard directly which would also diminish the amount of light emittedfrom the key members. Though troublesome, this disadvantage can beovercome using the above described material from MKS, Inc. which it isbelieved can withstand the cyclic compression stemming from theactuations of the key members.

Luminescent planar sheets can be constructed by those skilled in the artusing various technologies. For example, the luminescent planar sheetsmay be constructed of an electro luminescent lamp, an Organic LightEmitting Device (OLED), a Transparent Organic Light Emitting Device(TOLED), or a Flexible Organic Light Emitting Device (FOLED).Alternatively, the luminescent sheet may be constructed of asubstantially translucent material which acts as a “light pipe”connected to an independent light source such a fiberoptic light source,light emitting diodes, or light emitting crystals. In still anadditional embodiment, the luminescent sheet is constructed of aplurality of fiberoptic strands laid side-by-side to form a sheet whichconnects to an independent light source such as light emitting diodes orlight emitting crystals. The translucent material channels the lightfrom the light source to the keys, or to a separate light channelingmembrane 37 to illuminate the keys.

With reference to FIGS. 18-24, a preferred light guide 49, also referredto herein as a luminescent planar sheet, includes a translucent plate 71constructed in any number of shapes and sizes, but which is preferablyconstructed to have an elongate rectangular cross-section so as to havea top 73, bottom 75 and four sides 77. The translucent plate may be madeof any of the numerous light-transmitting materials, but which ispreferably made of an acrylic or polycarbonate material for cost andweight reasons. The plate further includes one or more cavity 79′ whichare recesses which project upwardly from the translucent plate's bottomsurface 75 towards the interior of the translucent plate. The cavitiesmay be of any shape. However, they are preferably hemispherically orelliptically dome-shaped so as to appear circular when looked upon fromthe plate's upper side. The cavities may be entirely empty except forair. Alternatively, the cavities may be filled with a translucent orentirely transparent material. Alternatively, the material in the cavitymay be colored and may be independently light producing, such as byincluding a phosphoric component which will tend to glow upon contactwith light, even light out of the visual spectrum. Of importance, thetranslucent plate and one or more cavities form a plate-cavity interface81 which, due to material properties and the curvature of the interface,will cause light to both reflect and refract when striking the interface81.

A preferred light guide 49 of the present invention further includes areflector 83. The reflector is positioned to cover the translucentplate's underside as well as cover the bottom of the cavities 79′. Asshown in FIGS. 21-24, the reflector may also cover the sides 77 of thetranslucent plate. Moreover, the reflector may cover the translucentplate's upper surface, except for where holes 84 are formed directlyover the light guides' cavities 79′. The reflector includes a highlyreflective surface, and thus it is preferably mirrored, white, lightgrey, silver, metallic silver or metallic gold so that light strikingthe reflector will reflect off the reflector as opposed to be beingabsorbed or refracted. In addition, the reflector may incorporateglowing or phosphoric elements which will emit light upon experiencinglight from another light source.

As shown in FIGS. 20-24, the light guide also includes one or more lightsources 85, which are preferably LEDs. The LEDs are preferablypositioned to project into recesses formed in the light guide's sides ortop or bottom surfaces, as shown in FIG. 19. Alternatively, the lightsources must be positioned near enough to the translucent plate so thatlight is received within its interior.

With reference to FIGS. 21 & 22, light rays 87 are transmitted into andthrough the translucent plate 71 by LEDs 85. Thereafter, the light rayswill tend to reflect off the translucent plate's top and bottom surfacesand sides, preferably with little absorption or loss as a result of areflector 83 covering these regions, until the light strikes theplate-cavity interfaces 81. Depending on the angle of incidence betweenthe light rays 87 and plate-cavity interfaces 81, and depending onvarious other factors such as the nature of the light, the material ofthe translucent plate and the possible presence of material within thecavity, the light will either reflect from the interface or refract intothe cavity. As a result of its dome-like shape, the refracted light 87 awill refract, in other words bend, downwardly through the cavity 79′until striking and reflecting off the reflector 83. The originallyrefracted and now reflected light will again refract into thetranslucent plate until it is transmitted from the translucent plate'stop 73. Meanwhile, as a result of the cavities preferably dome-likeshape, the reflected light 87 b will also be directed upwardly untilbeing transmitted from the translucent plate's upper surface immediatelyabove the cavity 79′.

The reflection and refraction properties of the plate-cavity interfacecan be modified as can be determined by those skilled in the art. Forexample, polishing or roughening the plate cavity interface, such as bymachining or sand blasting, can alter the refraction and reflectionproperties until optimal light transmission from the translucent plate'supper surface is obtained.

In addition to the traditional rectangular shape of the light guideshown in FIGS. 18 -19, the light guide 49 may be modified to increasethe transmission of light to areas of the light guide which areundesirably dim. For example, as shown in FIG. 20, one or more of thelight guide's corners 93 may be rounded to reduce light loss that canoccur in a sharp angled corner. In addition, one or more of the corner's97 can be truncated at various angles to direct light to differentregions of the light guide. In operation, and shown in FIG. 20, lightrays emitted from LED's can be reflected off a truncated corner to faraway areas of the keyboard where an LED is not in the vicinity. Inaddition to rounding or truncating the light guide's corners, the lightguide can be machined or molded to include reflecting cut-outs 95, whichcan be in various shapes, for directing light to desired areas. Forexample, still with reference to FIG. 20, light transmitted from oneside of light guide can be reflected with a “V” shaped cutout 95 todistribute light to far corners of the keyboard. Moreover, a cutout 95can be used for placement or angling of the LEDs in order to emit lightmore uniformly within the light guide.

Still additional modifications can be made to the edge of thetranslucent sheet 71 to increase light transmission. For example, in afirst embodiment, the edge is curved or rounded to provide a smoothexterior with no sharp edges so as to reduce light loss in a corner.Alternatively, as shown in FIGS. 18, 19 & 21-24, the edge is machined ormolded to include a recess sized for receipt of any wires 91 used forsupplying power to light sources 85. For this embodiment, it ispreferred that any wires positioned within the edge recess be coatedwith a reflective material such as white paint or white plasticinsulator. As shown in FIGS. 22-24, the reflector 83 may be positionedto cover the wire 91 to maintain it in place, and to reflect any lightback into the interior of the translucent plate 71 that otherwise mightescape.

As explained in much greater detail below, the light guides 49 of thepresent invention will have application for illuminating variousstructures, and particularly for illuminating the keys of a keyboard.For example, FIG. 23 illustrates a simplified keyboard having aplurality of keys members 11 and a translucent printed circuit board 21.Though not shown, the keyboard may include an upper clam shell member, alower clam shell member, and a preferably translucent biasing means,such as an elastomeric diaphragm, for biasing the keys upward. The lightsource 85 emits light into the translucent plate 71 where it isreflected until striking the plate-cavity interface 81. Light is thenreflected and refracted in the manner described above until beingtransmitted upwardly to the keys 11. As shown, the keyboard preferablyincludes an upper reflector 83 for further trapping the light untiltransmission to the key members through holes 84.

As shown in FIG. 24, the light guide 49 of the present invention is alsosuitable for illuminating the keys for keyboards which incorporatemembrane switch technology in which the circuit board 21 incorporates aplurality of flexible buttons which upon depression, activates a key.Membrane switch keyboards are commonly used for cellular telephones,remote controllers, ATM machines, etc.

As shown in FIGS. 23 and 24, the light producing cavities can becentered directly under the keys of a keyboard. However, alternatively,the cavities may be displaced off-center from directly below a keymember. In particular, it has been found that displacing the lightproduced by the cavity 79′ under a key approximately 1-5 millimeters canmake the key characters, depending on their size and placement, toappear more luminous. Moreover, displacement of the cavities relative tothe center of the key may be of particular importance where charactersare offset from the center of the key, such as for function or numberkeys, or keys having multiple different characters such as the keyboardkey showing a “!” and “1”. Moreover, key members at the top of akeyboard are typically viewed at a greater angle to vertical than keysat the bottom of a keyboard. As a result in this change in angle, it hasbeen found that displacing the light produced by the cavities 79′rearwardly for keys positioned toward the back of the keyboard willincrease the apparent luminosity of the key characters. Thus, in a firstembodiment, the light produced by the cavities 79′ under the lower keysincluding shift, ctrl, spacebar and letters in the rows corresponding toz, x, c, a, s, d, etc. are not displaced relative to the key membercenter. However, the cavities, and light produced by them, are displacedrearwardly in keys at the top of the keyboard such as the function keysand number keys. In still an additional embodiment, the displacement ofthe cavities, and the light produced by them, increases incrementallyfrom the bottom of the keyboard toward the top of the keyboard. Thus, asbut an example, there may be no displacement of the cavities at thebottom row of the keyboard, but the cavities may be displaced rearwardly1 millimeter in the second row from the bottom, 2 millimeters in thethird row from the bottom, 3 millimeters in the fourth row from thebottom, etc. As would be understood by those skilled in the art, thedisplacement of the light produced under keys can be applied to lightguides and light sources other than those described herein.

FIGS. 25-29 illustrate an additional embodiment of an luminescent planarsheet which is ideal where the luminescent sheet needs to beparticularly thin such as is required for laptop keyboards. Theluminescent sheet includes a light guide 49 which does not includeupwardly projecting cavities. Instead, the light guide 49 has a flatunderside surface and reflective members 79″ are positioned underneatheach of the keys. As illustrated in the FIGS. 25-29, each reflectivemember 79″ causes light, provided by LEDs 85 positioned along the sidesof the light guide, to reflect upward toward each overlying key. Thereflective members 79″ may be made of paint or other coating appliedupon the bottom of the light guide. Alternatively, the reflective member79 may be comprised of thin reflective paper or plastic or the like.Still additional constructions for the reflective members may be devisedby those skilled in the art.

Preferably, an additional reflective sheet 83 covers the underside ofthe light guide 49 as well as the reflective members 79″. Alsopreferably, the reflective members 79″ provide greater light diffusionthan the reflector. In a preferred embodiment, the reflective membershave a “flat” white appearance which is understood to provide highreflectivity and relatively good light diffusion. Preferably for thisembodiment, the reflector has a “glossy” white appearance which isunderstood to provide excellent reflectivity but lower diffusion.

As illustrated in FIGS. 25-26, in preferred embodiments, the reflectivemembers are reflective white circles or squares ¼-¾ inch across, with apreferred width of approximately ½ inch. The white reflective membersare preferably “flat white” in appearance to provide light diffusion.The reflective members are then covered by a sheet of glossy paper,plastic or the like 83 having a mirrored, white, light grey, silver,metallic silver or metallic gold appearance which provides lesserdiffusion than the overlying reflective members.

As shown in FIGS. 25-29, the reflector may also cover the sides 77 ofthe light guide 49. Moreover, the reflector may cover the translucentplate's upper surface, except for where holes are formed directly overthe light guides' reflective members 79″. The reflector includes ahighly reflective surface, and thus it is preferably mirrored, white,light grey, silver, metallic silver or metallic gold so that lightstriking the reflector will reflect off the reflector as opposed to bebeing absorbed or refracted. Also for this embodiment, the reflector mayincorporate glowing or phosphoric elements which will emit light uponexperiencing light from another light source.

With reference to FIGS. 14 and 15, in still an additional embodiment ofthe invention, the keyboard's upper clamshell member includesilluminated indicia for identifying the function of one or more keymembers. Sometimes key members are too small for including symbols whichare sufficiently large so as to be easily read by a keyboard operator.This is particularly true of the “function” keys which are often foundat the top of a typical keyboard. These function keys include thetraditional “F1-F12” keys, as well as “insert”, “home”, “delete”, “end”,“page up” and “page down” keys. Further, more and more keyboards areconstructed to include “internet” keys which provide access toparticular websites, and audio and video keys which control a computer'saudio and video functions. In addition, keyboards are being constructedwith more and more function keys, and the invention is not intended tobe limited to the use of the function keys identified herein.

Unfortunately, these “function” keys are often constructed smaller thanthe “qwerty” letter keys. Due to their small size, it is often difficultto incorporate a symbol, or indicia, on the key members which can beeasily read by the keyboard operator. Moreover, incorporating anilluminated symbol on these keys in accordance with FIGS. 4-13 can makethe symbol even more difficult to read.

In order to overcome these disadvantages, in a preferred embodiment ofthe invention, the keyboard's upper clamshell member is constructed toinclude a region that is partially translucent. This region, constructedof a substantially translucent material, communicates light rays throughthe keyboard to display indicia indicating functions of one or moremembers. In similar fashion to the illumination of symbols shown inFIGS. 3 and 11, the clamshell indicia may be illuminated by lightchanneling through the upper clamshell to be emitted in the form of theindicia wherein an opaque coating or material is used to restrict thelight to the shape of the indicia 57. Alternatively, larger portions ofthe clamshell member 15 can be illuminated while the symbol 57 remainsopaque, depending on whether the symbol is intended to be illuminated asa positive or negative representation.

Moreover, the clamshell indicia may be illuminated using an illuminatingplanar sheet as shown in FIGS. 7-10, or the clamshell indicia may beilluminated using a light pipe as shown in FIGS. 11-13. For example, asshown in FIG. 14, in a first embodiment, the keyboard includes adiaphragm 19, first and second printed wiring layers 23 and 27, aninsulator or dielectric layer 25, and a light channeling structureconstructed as a substantially planar sheet 49. A light source 59, suchas an LED, is provided for emitting light upwardly from the planar sheet49, through the printed circuit board and elastic diaphragm so as tostrike the underside of the upper clamshell member 15. The upperclamshell member includes translucent regions 57 to provide illuminatedindicia for identifying the functions of the adjacent key members 11.

In an additional embodiment, a light pipe 47 is utilized to illuminatethe clamshell indicia 57 and key members. As shown in FIG. 15, theindica 57 reading “ORTS” is a portion of the complete word “SPORTS” foridentifying the internet function of a key member 11 which providesaccess to an internet website dedicated to sports. The keyboard includesa clamshell member 15, illuminated indicia 57, key members 11,illuminated symbols 35, a biasing projection 20 and a light pipe 47. Thelight pipe 47 is attached to, or formed integral with, the upperclamshell member 15, adjacent to the hollow projections 39. The surfaceof the light pipe 47 is scratched or otherwise flawed so as to reflectlight rays from the interior of the light pipe 47 to be emitted from thelight pipe's 47 exterior surface. Light is emitted upwardly so as toilluminate the translucent regions 57 of the upper clamshell member.

With reference also to FIGS. 11-15, preferably light is also emittedlaterally from the light pipe so as to strike the hollow projections 39.Preferably, the hollow projections 39 are constructed to include aportion that is at least partially translucent to allow light channeledby the light pipe 47 to project into the bores onto the key shafts 29 ofthe key members 11. Alternatively, the hollow projections 39 haveopenings (not shown) in their sidewalls to allow light to projectlaterally from the light pipe 47 through the openings and onto theexterior of the key shafts 29 of the key members 11. The light channeledby the light pipe 47 strikes the sides of the key shafts 29 and istransmitted through the translucent material of the key member 11 to beprojected from the top of the key cap 31 in the form of a symbol 35.

The keyboard including illuminated clamshell indicia has been describedprimarily for use in connection with illuminating and identifyingfunction keys.

However, the invention is not intended to be limited thereto. Forexample, a keyboard having an upper clamshell member includingilluminated indicia for identifying the “qwerty” key members is alsowithin the scope of the invention.

Preferably, the key members are also constructed, at least partially, ofa translucent material so that the key members illuminate. The keymembers may be constructed in various ways. For example, the keys may besubstantially translucent with minimal coating except for symbols, suchas letters on the keys, to provide a highly luminous key. However,preferably the keys are constructed in opposite manner in which the keysare substantially covered by an opaque material except for the symbolsto provide key members including illuminated symbols for identifyingtheir function.

Where the key members are too small for readable markings, preferablythe key members include an illuminated region, such as in the shape of acircle or star, for providing an indication as to the location of thekey members.

In a preferred embodiment of the invention, translucent portions of thekeyboard are coated on their exterior surfaces with a reflective opaquecoating where light is not intended to be emitted. More particularly, itis preferred that the key members are coated with a paint such as lightgrey, white, silver, metallic silver, metallic gold, and other shinymetallic colors which substantially reflects visible light. Where theupper clamshell member is constructed of a translucent material, it isalso preferred that the upper clamshell be coated with a material forreflecting visible light and reducing light absorption.

Though not shown in the figures, in still an additional preferredembodiment, the key caps and clamshell member include two layers ofpaint or the like. The initial first coating is a highly reflectivematerial to reduce visible light absorption and reflect the light backinto the translucent material until transmitted from the key caps.Meanwhile, a second coating of an alternative paint or other material isapplied over the first coating. The second coating may also bereflective of visible light. However, it is preferred that the secondcoating reflects less visible light than the first coating, andpreferably the second coating is a substantially non-reflective coatingor color such as dark grey, black or blue. The keys can be made bysequentially application of coatings to translucent key members. Thesymbols, such as letters, are then formed on top of the key caps byusing a laser or the like to cut away the excess material of both thefirst and second coatings to form the desired symbols. Key members arethus produced which include an enhanced contrast between the luminescentsymbol and the substantially non-reflective regions of the key cap toprovide enhanced readability for the keyboard user.

Luminescent keyboards have been created with luminescent key caps andopaque lettering, as well as their visual negative, opaque key caps withluminescent letters 35 such as illustrated in FIGS. 3-6. Keyboards withopaque key caps and luminescent letters are considered visuallypreferable. Unfortunately, this construction does not provide aluminescent indicator for the location of the space bar, and personsworking in dark environments are not provided an indication as to theplacement of the space bar. More specifically, all keys of a traditionalkeyboard, except for the space bar, include visual indicia identifyingthe function and placement of the key member. Even recently introduced“function” keys and Internet keys, typically include visual indiciawhich can be illuminated for identifying key functions and placement.However, the space bar does not have an accepted symbol or identifierfor indicating its function, so prior art luminescent keyboards withopaque keys caps and luminescent letters have left the space barcompletely opaque. This is particularly problematic because the spacebar is the largest key member of a traditional keyboard, and people tendto look for this key member first when placing their fingers on akeyboard. This has not been a problem for key boards which haveincorporated luminescent key caps and opaque letters as manufacturershave simply illuminated the entire space bar.

With reference to FIG. 16, a preferred keyboard with opaque key caps andluminescent letters includes a space bar 61 with a luminescent lineextending laterally across the top face of the space bar for indicatingthe space bar's function and position. The line may be dotted or dashed.Moreover, a plurality of laterally extending lines may be providedacross the face of the space bar. However, as shown in FIG. 16, a singlecontinuous luminescent line is considered preferable.

As shown in FIG. 17, in an alternative embodiment of the invention forilluminating the space bar 61, the space bar includes a luminescentdecorative design 65 for indicating the space bar's position.Preferably, and as illustrated in FIG. 17, the decorative design 65 isprovided in the form of a manufacturer's or distributor's logo ortrademark. As the largest key member of a traditional keyboard, andbecause the space bar does not include an accepted indicia forindicating its function, the space bar provides an ideal size andlocation for placement of a company's logo or design.

The present invention provides for an inexpensive and simple way tomanufacture keyboards including illuminated indicia and keys havingilluminated upper surfaces. The keyboard of the present invention isparticularly suitable for use with computers and particularly withlaptop computers, though it is not intended that the present inventionbe limited thereto. While several particular forms of the invention havebeen illustrated and described, it will be apparent that variousmodifications can be made without departing from the spirit and scope ofthe invention. Accordingly, it is not intended that the invention belimited except by the following claims.

We claim:
 1. A light guide comprising: an at least partially translucentlight transmitting plate having an upper surface, a lower surface andside surfaces; at least twenty-six light transmitting cavitiesprojecting into said lower surface of said plate, said twenty-sixcavities each having an arcuate dome-shaped sidewall so that saidcavities are hemispherical or hemi-ellipsoid in shape, the interfacebetween said plate and said twenty-six cavities defining twenty-sixplate-cavity interfaces; a reflector covering at least a portion of saidplate's lower surface and said twenty-six cavities; and a light sourcefor communicating light through said plate; said interfaces being atleast partially translucent for allowing light transmitted through saidplate to refract through said interfaces into said cavities, and saidcavities being at least partially translucent to permit light refractedinto said cavities to reflect off said reflector to again refractthrough said interfaces to travel upwardly through said plate totransmit light from said plate's upper surface.
 2. The light guide ofclaim 1 wherein said interfaces are partially reflective so as toreflect light from said light source upwardly through said plate totransmit light from said plate's upper surface.
 3. The light guide ofclaim 1 wherein said reflector covers said side surfaces.
 4. The lightguide of claim 1 wherein said reflector covers said top surface exceptin places where light is to be emitted.
 5. The light guide of claim 1wherein said reflector is white, light grey, silver, metallic silver ormetallic gold.
 6. The light guide of claim 1 wherein said cavities arefilled with air.
 7. A lighted keyboard comprising: at least twenty-sixlight transmitting keys members; an at least partially translucent lighttransmitting plate underlying said key members having an upper surface,a lower surface and side surfaces; at least twenty-six lighttransmitting cavities projecting into said lower surface of said plate,said twenty-six cavities each having an arcuate dome-shaped sidewall sothat said cavities are hemispherical or hemi-ellipsoid in shape, theinterface between said plate and said at least twenty-six cavitiesdefining at least twenty-six plate-cavity interfaces; a reflectorcovering at least a portion of said plate's lower surface and said atleast twenty-six cavities; and a light source for communicating lightthrough said plate; said interfaces being at least partially translucentfor allowing light transmitted through said plate to refract throughsaid interfaces into cavities, and said cavities being at leastpartially translucent to permit light refracted into said cavities toreflect off said reflector to again refract through said interfaces totravel upwardly through said plate to transmit light from said plate'supper surface to illuminate said key members.
 8. The lighted keyboard ofclaim 7 wherein said interfaces are partially reflective so as toreflect light from said light source upwardly through said plate totransmit light from said plate's upper surface to illuminate said keymembers.
 9. The lighted keyboard of claim 7 wherein said reflectorcovers said side surfaces.
 10. The lighted keyboard of claim 7 whereinsaid reflector covers said top surface except in places where light isto be emitted.
 11. The lighted keyboard of claim 7 wherein saidreflector is white, light grey, silver, metallic silver or metallicgold.
 12. The lighted keyboard of claim 7 wherein said cavities arefilled with air.